Gaskets are used as a joint for pipes in various plants of petrochemistry, petroleum processing, electric power and paper manufacturing, for example. Gaskets fill spaces and at the same time prevent leakage of fluids or incorporation of extraneous materials from the outside.
When a gasket is used in a plant for producing a monomer such as butadiene, styrene and acrylonitrile, a monomer produced penetrates the gasket and polymerizes whereby the gasket swells to clog a pipe (so-called flower phenomenon) or the gasket itself is broken due to swelling. In addition, for a gasket with a large opening, the gasket is corroded by monomer polymerization inside the gasket, thereby leading to monomer leakage. The swelled gasket peels to contaminate a product.
Patent Document 1 discloses a sealing material that can have a low swelling ratio relative to a gaseous monomer. However, the sealing material does not have a sufficient swelling resistance and the production of large size products using the sealing material is difficult due to the poor mold-releasing property and productivity thereof. Although there are various descriptions in Patent Document 1, the only practically-available sealing material is one obtained by adding an amine compound as a polymerization inhibitor to tetrafluoroethylene-perfluoro(alkylvinyether) copolymer (PFA). Current products are high at cost and blackish. The market requires whitish products.